Can SUVmax values of Ga-68-PSMA PET/CT scan predict the clinically significant prostate cancer?

PURPOSE: The intensity of prostate-specific membrane antigen (PSMA) expression increases as the tumor grade increases and the uptake of Ga-68-PSMA is higher in high-grade tumors. The aim of the present study was to evaluate the correlation of preoperative tracer uptake of primary tumor to Gleason Score in patients who underwent prostatectomy. PATIENTS AND METHODS: We retrospectively evaluated 141 patients who had Ga-68-PSMA positron emission tomography/computed tomography (PET/CT) imaging and who underwent prostatectomy. All patients had a diagnosis of prostate cancer on the basis of 10-24 cores transrectal ultrasound-guided biopsy (TRUS-Bx). Histological assessment was performed according to the New Contemporary Prostate Cancer Grading System. All patients had a prostate-specific antigen (PSA) level measurement within maximum of 28 days before Ga-68-PSMA PET/CT. Region of interests were drawn manually around the prostate gland, avoiding the bladder activity, to calculate the maximum standardized uptake values (SUVmax) values. RESULTS: The median PSA values for all patients were 10.0 ng/ml. PSA values for low-risk patients were significantly lower than those of high-risk patients (P<0.001). There were 41.1% upgrades and 7.8% downgrades following prostatectomy in terms of Grade Groups. According to the final pathology reports, 21% (n=16) of patients moved from a low-risk level (grade groups 1+2) to a high-risk level (grade groups 3+4+5). The median SUVmax value was 8.8, ranging from 2.1 to 62.4. There was a strong correlation between SUVmax values and grade groups (Pearson ρ=0.66) (P<0.001). The mean SUVmax values of high-risk patients were significantly higher than those of low-risk patients (18.9±12.1 vs. 7.16±6.2, respectively) (P<0.001). Receiver operation characteristic curve analysis of SUVmax at the cut-off value of 9.1 showed a high sensitivity (78%) and specificity (81%) for detection of high risk disease. CONCLUSION: SUVmax values correlate significantly with the grade groups of the primary tumor. The intraprostatic accumulation sites may predict clinically significant cancer and potentially serve as a target for biopsy sampling in conjunction with mpMRI in selected patients.

177Lu-DOTATATE therapy in patients with neuroendocrine tumours including high-grade (WHO G3) neuroendocrine tumours: response to treatment and long-term survival update.

PURPOSE: Upon diagnosis, distant metastases are encountered in 21-50% of neuroendocrine tumours (NETs). However, few systemic treatment options are available for the well-differentiated NETs in the metastatic stage. Lu-DOTATATE is one of the most effective treatments in this limited patient group. We retrospectively investigated its efficacy and effect on the survival in patients with both well-differentiated and grade III NETs who had high uptake in pretherapeutic Ga-DOTATATE PET/computed tomography scans. PATIENTS AND METHODS: Patients with metastatic NETs treated with Lu-DOTATATE between January 2010 and November 2015 in our department were included in this retrospective cohort. Toxicity and adverse effects were evaluated according to SWOG criteria. Progression-free survival (PFS) and overall survival (OS) rates were calculated considering the first date of treatment. Response was evaluated according to RECIST criteria. Potential predictors of survival and response were analysed. RESULTS: Patients (n=186) with metastatic NETs originating from various primary sites (bronchial, pancreatic, nonpancreatic gastroenteropancreatic-NETs, pheochromocytoma-paraganglioma and unknown primary) were treated with 1107 courses of Lu-DOTATATE treatment (median: 6; range: 3-12). Among 160 patients whose responses to treatment could be evaluated according to the RECIST criteria, 28.1% (n=45) had a progressive disease, 21.9% (n=35) had a stable disease, 46.9% (n=75) had a partial response and 3.1% (n=5) had a complete response. Median follow-up was 30.6 months. The Kaplan-Meier estimated median PFS was 36.4 months, mean PFS was 38 months and the mean OS was 55 months. The disease control rates in patients with WHO grades I, II and III were 74, 73 and 60%, respectively, and the OS rates were 61.9, 52.2 and 38.4 months, respectively. We observed no major renal toxicity except a minor increase (11.1%) in average serum creatinine levels. In 33.9% (n=56) of the patients, grade I toxicity; in 9.1% (n=15), grade II; and in 1.2% (n=2), grade III toxicity were observed. CONCLUSION: Lu-DOTATATE therapy is an important treatment option in somatostatin receptor type-2-positive pancreatic, nonpancreatic gastroenteropancreatic-NETs, and lung NETs including metastatic NETs with an unknown primary site and significantly contributed to patients' OS. Additionally, peptide receptor radionuclide therapy may have a role in a selected subgroup of patients with grade III NET with high somatostatin receptor type-2 expression.